feat: add sops

We've previously used SOPS for our secrets management and liked it. We
did, however, find the configuration was a bit annoying to do. In aid of
this, we've made a SOPS module that we find a little easier to make the
sort of configurations we want without creating so much mess.

We haven't set up scalpel/equivalent yet - we intend to avoid it if at
all possible. It isn't necessarily out-of-scope but it isn't included in
our current SOPS plans.

Change-Id: I35b9c7e94c12a4f1360833026efe06803d59626e
Reviewed-on: https://git.clicks.codes/c/Infra/NixFiles/+/725
Reviewed-by: Samuel Shuert <coded@clicks.codes>
Tested-by: Samuel Shuert <coded@clicks.codes>
diff --git a/configure.sh b/configure.sh
new file mode 100755
index 0000000..7ff1090
--- /dev/null
+++ b/configure.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# SPDX-FileCopyrightText: 2024 Clicks Codes
+#
+# SPDX-License-Identifier: GPL-3.0-only
+
+nix eval -f .sops.nix --apply "(f: f (builtins.getFlake \"nixpkgs\"))" --json > .sops.yaml # regenerate the "yaml" so you can add secrets